Since the points lie in the plane, the vectors and
are parallel to the plane.
The cross product:
is normal to the plane.
Use this normal and the point (8,3,1):
And we get:
Now, try the other method.
The plane that contains the points (8,3,1), (2,6,3), and (4,6,2) has an equation of the form ax+by+cz=d. Find coefficients fr this equation, trying two different approaches to the problem. One method uses vectors, another does not.